In previous studies we have described various aspects of the dispersion, chromatographic behavior, and kinetics of various adenylate cyclases. The study of the enzyme's kinetics has been extended to the hormonally-sensitive adenylate cyclase of platelets and liver. We have been investigating the mechanisms by which hormones, fluoride, and guanine nucleotides stimulate adenylate cyclase, the properties of the formation of adenosine, and the mechanisms of stimulatory and inhibitory actions of adenosine on adenylate cyclase. Our immediate objectives in the proposed studies are to complete current studies on the mechanisms of adenosine inhibition of adenylate cyclase. Otherwise full energies will be given to: a) confirming and extending studies on the possible role of phosphorylation-dephosphorylation in the control of adenylate cyclase by using purified preparations of cAMP-dependent and -independent protein kinases and the protein kinase inhibitor; and b) the application of previously established chromatographic systems to a larger scale purification of the cerebellar enzyme with emphasis being placed on several affinity chromatography systems and on enzymic disruption of membrane or enzyme aggregates. BIBLIOGRAPHIC REFERENCES: Johnson, R.A., and Garbers, D.L. (1976) Kinetics of hepatic adenylate cyclase. Fed. Proc. 35(7): 1437. Johnson, R.A. (1977) Hydrolysis of 5'-adenylyl-imidophosphate (AMP-P(NH)P); Implication for the study of adenylate cyclase. Fed. Proc. 36(3): 763.